US STOCKS-Wall St slumps more than 1.5 pct as oil plumbs 7-yr low
* Oil plunges to 7-year lows
* Fed to decide on interest rate hike next week
* Volatility index at its highest level since early October
* DuPont, Dow Chemical fall after agreeing to merge
* Indexes down: Dow 1.65 pct, S&P 1.74 pct, Nasdaq 1.97 pct (Updates to early afternoon)
By Tanya Agrawal
Dec 11 (Reuters) - All three major indexes extended losses on Friday, falling more than 1.5 percent, and were on track for their worst weekly performance in a month as growing oversupply concerns dragged down crude oil prices to their 7-year lows.
The International Energy Agency said it sees the oil glut worsening in 2016 as demand slows and OPEC shows no signs of slowing production.
The steep drop in oil prices adds to investor uncertainty as the U.S. Federal Reserve prepares to raise interest rates for the first time since June 2006 at its meeting next week. Continuación...